Abstract [en]

The effect of sediment composition on the growth of Potamogeton pectinatus and Myriophyllum spicatum was evaluated by a greenhouse experiment in which segments of both species were grown on 37 sediments, which ranged from highly flocculent to sandy, collected from the calcareous, shallow eutrophic Lake Krankesjon. The two species responded similarly to the 37 sediment types; there was a strong correlation between the find biomass of M. spicatum and the find biomass of P. pectinatus for a given sediment type. Our results indicated that in these sediments, organic matter and density were not effective predictors of macrophyte growth. Root:shoot ratios of both P. pectinatus and M. spicatum were inversely related to the final biomass, and phosphorus and nitrogen concentrations of M. spicatum shoots were inversely related to root:shoot ratios. This suggests that plants were responding to sediment infertility by allocating proportionately more growth to root formation. Tissue analysis indicated that M. spicatum growth was phosphorus limited on some sediments, and this may have been a result of reduced phosphorus availability due to binding with calcium.